The seven-member crew, slated to return to Earth on Friday, successfully completed their ambitious to-do list for the 11-day mission, which included installing two new science instruments and repairing two ailing ones.

The repairs were tricky, though, because the individual instruments aboard the 19-year-old observatory had not been designed to be fixed in space.

"If we actually repair the two broken instruments ... we'll have the best Hubble ever--there's no question," Edward Weiler, who leads NASA's science division, had said before the launch.